424 SOME NATURAL HISTORY RECORDS. 



How flowers respond to climatic influences was strikingly 

 set forth by the hazel and the common sallow. When our winters 

 are severe, the pistiliferous and stameniferous flowers of these 

 trees attain their functional activity almost simultaneously. 

 On the other hand, when the winters are mild and humid, 

 the stameniferous flowers open many days — in some cases even 

 weeks — before the pistiliferous ones, the result being a great 

 scarcity of fruit. It is an old observation that the development 

 of stamens is always correlated with a relatively high temp- 

 erature, and that the first few warm days which follow a severe 

 winter bring forth the stameniferous flowers on diclinous trees 

 before the pistiliferous ones, as well as mature the stamens on 

 hermaphrodite flowers before the pistils. 



Shortly after Christmas, by the first week in January, in 

 fact, most of our hazel trees were bountifully arrayed in male 

 catkins. None of the female flowers were then to be seen, and 

 when the latter did unfold a week or two later the male flowers 

 had shed most of their pollen. The sallow behaved in a similar 

 manner, the golden catkins of the male flowers being ripened 

 long before their less attractive female ones, thereby rendering 

 fertilisation of the majority of ovules impossible. Indeed, if 

 evidence were wanting to prove that a winter of ordinary 

 severity secures a greater amount of fruit and seed on early 

 flowering plants than one of a relatively high temperature, the 

 hazel and the sallow have offered abundant proof this year. 

 What is required is that the stamens and pistils shall mature at 

 the same time ; and as the development of the pistil coincides 

 with a vigorous growing condition in the plant, and that of the 

 stamens with a rise in temperature, it follows that the longer 

 the ripening of the stamens is delayed, the more certain is the 

 plant of fertilisation. 



When we come to our migratory birds, we find that, with 

 the exception of the swallow, they arrived on our shores 

 earlier than usual. The dates for their arrival in the Kennall 

 Valley are as follow : 



Stone-chat (male and female) . . March 1 7th. 



Swallow , ,, 24th. 



Chiff-chaff (male) . . . . April 1st. 



Po. (female) .. .. ,, 19tlj, 



